Vehicles may include a coolant system configured to reduce overheating of an engine by transferring the heat to ambient air. Therein, coolant is circulated through the engine block to remove heat from the hot engine, and the heated coolant is then circulated through a radiator near the front of the vehicle. Heated coolant may also be circulated through a heat exchanger to heat a passenger compartment. The coolant system may include various components such as various valves, pumps, and one or more thermostats. In the event of coolant system degradation due to component malfunction (e.g., water pump degradation), or due to loss of coolant from the cooling system (e.g., due to a coolant leak), the engine may overheat. Engine overheating may be exacerbated in turbocharged direct injected engines which tend to run hot due to boost and higher loads.
Various approaches have been developed to address engine overheating in the event of coolant system degradation. One example approach, shown by Willard et al. in U.S. Pat. No. 9,217,379, addresses engine overheating by alternately shutting down fuel to one or more cylinders while maintaining vehicle torque demand with the fueled cylinders. Cylinder cooling is achieved as cool un-combusted air flows through the unfueled cylinders. In still other approaches, cylinder fueling may be shut off on a bank-wise basis to cool the deactivated bank, while the active bank continues to generate torque for vehicle propulsion.
The inventors herein have recognized potential issues with the above approach. As one example, in engines configured with start-stop (S/S) capabilities, even with all cylinders deactivated, under-hood temperatures may continue to climb. Due to the vehicle being static and not moving, even if additional cooling fans are activated, the idle-stopped engine may continue to overheat. If the engine is restarted to increase cooling air flow, the fuel economy benefit associated with the start-stop operation may be compromised.
The inventors herein have developed systems and methods to at least partially address the above issues. In one example a method comprises activating an electric compressor in an intake of an engine of a vehicle, to direct an air flow through a first single cylinder of the engine during a start/stop event where the engine is not combusting air and fuel, to reduce a temperature of the first single cylinder to a desired temperature prior to a request to restart the engine. In this way, mitigating action may be taken at a S/S event for a single cylinder that is identified as overheating, which may prevent or reduce potential engine degradation stemming from the single overheating cylinder.
In one example of the method, the method further includes positioning the first single cylinder with both an intake valve and an exhaust valve of the first single cylinder in an at least partially open configuration, to direct the air flow through the first single cylinder. By positioning the first single cylinder as such, the first single cylinder may be effectively cooled during the S/S event.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.